The role that plastic-frictional energy dissipation in the fracture process zone plays in the workof-fracture method for measuring the fracture energy of concrete or other quasibrittle materials is analyzed, and a possible improvement of this method is proposed. It is shown that by measuring the unloading compliance at a sufficient number of states on the post-peak descending load-deflection cu...

A new method is used to quantify the relationships between stress field and primary fracture characters (aperture, density) in low-permeability sandstone reservoirs based on laboratory experiments and mathematical development, through which, quantitative fracture modeling is set up. Using this modeling, we can load it into the stress analysis software (Ansys 10.0) to acquire 3D palaeo stress fi...

We study size effects in the fracture strength of notched disordered samples using numerical simulations of lattice models for fracture. In particular, we consider the random fuse model, the random spring model and the random beam model, which all give similar results. These allow us to establish and understand the crossover between a regime controlled by disorder-induced statistical effects an...

A 30-year-old patient sustained the fracture in a motorcycle accident. A triplane-type of fracture of the distal femur was confirmed by CT scan. The trochlear fragment was reduced anatomically and was stabilized with 6.5mm cannulated screws. Once reconstruction of the coronal plane fracture was performed, the split lateral condylar fragment was fixed with a cannulated screw to the medial fragme...

PURPOSE The purpose of this study was to investigate the fracture loads and mode of failure of all-ceramic crowns fabricated using Top-Ceram and compare it with all-ceramic crowns fabricated from well-established systems: IPS-Empress II, In-Ceram. MATERIALS AND METHODS Thirty all-ceramic crowns were fabricated; 10 IPS-Empress II, 10 In-Ceram alumina and 10 Top-Ceram. Instron testing machine w...

Posterior malleolar fractures are a common component of ankle fractures. Between 7 and 44% of all ankle fractures involve the posterior malleolus (1). This type of fracture often arises from rotational injury and rarely occurs in isolation. The morphology of the fracture can be variable. A secondary type of posterior malleolar fracture is the posterior pilon variant. This involves a majority of...

The comprehensive fracture tests of notched and unnotched beams presented in the preceding paper are evaluated to clarify the size effects and fracture energy dissipation. The test results for beams with notches of various lengths agree closely with Bažant’s Type 2 size effect law and yield the value of the initial fracture energy Gf. Since nearly complete post-peak softening load–displacement ...

Fracture damage in trilayers consisting of outer and inner brittle layers bonded to a compliant (polycarbonate) substrate and subjected to concentrated surface loading is analyzed. The principal mode of fracture is radial cracking at the undersurface of the inner (core) layer, even in the strongest of core ceramics--other damage modes, including radial cracking in the outer (veneer) layer, are ...

The financial cost of using human tissues in biomedical testing and surgical reconstruction is predicted to increase at a rate that is disproportionately greater than other materials used in biomechanical testing. Our first hypothesis is that cadaveric proximal humeri that had undergone monotonic failure testing of simulated rotator cuff repairs would not differ in ultimate fracture loads or in...

The fracture resistance of structures is optimised using the level-set method. Fracture resistance is assumed to be related to the elastic energy released by a crack propagating in a normal direction from parts of the boundary which are in tension, and is calculated using the virtual crack extension technique. The shape derivative of the fracture-resistance objective function is derived. Two il...